Summary
Linuxfabrik Monitoring Plugins allow insecure creation of SQLite databases
Full technical description
The SQLite databases are created at predictable (static) paths in /tmp. Any user can therefore create a symlink at these paths in /tmp pointing to arbitrary files. The monitoring scripts then follows these symlinks and then creates their database at the symlink target.
This becomes really dangerous for the scripts which can be executed as root with sudo. With this, an attacker can write to abitrary paths.
PoC
The docker-stats check command here as an example. Because writing to /tmp is the default behaviour, the other check commands which use a SQLite database are also very likely affected.
# Create the symlink as nagios user
nagios@test-server:/tmp$ ln -s /root/nagios-was-here /tmp/linuxfabrik-monitoring-plugins-docker-stats.db
# Trigger the execution nagios user
nagios@test-server:/tmp$ sudo /usr/lib64/nagios/plugins/docker-stats
Check whether or not file was created.
root@test-server:/# file /root/nagios-was-here
/root/nagios-was-here: SQLite 3.x database, last written using SQLite version 3046001, file counter 2, database pages 3, cookie 0x2, schema 4, UTF-8, version-valid-for 2
Impact
In it's basic form, this vulnerbility can lead to a denial of service, impacting users who use the provided sudoers file and who didn't take any special precautions like systemd's PrivateTemp. It requires that an attacker already compromised the nagios account (which is quite a high barrier to be honest).
If any application on the server relies on a SQLite database, there are scenarios where this vulnerability allows for content in existing SQLite databases to be modified. An attacker could let the symlink point to an existing SQLite database and create in /tmp a specially-crafted SQLite Rollback Journal (.db-journal) or Write-Ahead-Log (.db-wal), which is then applied to the database.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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A proposed fix would be to create a separate directory inside /tmp per user (e.g., /tmp/linuxfabrik-monitoring-plugins-{os.geteuid()}). After creating this directory (or using an already existing one), check the following:
# Use os.lstat() instead of os.stat() so we don't accidentally follow symlinks
dir_stat = os.lstat(TMP_DIR_PATH)
# Ensure the directory is a real dir and not a Symlink
if not stat.S_ISDIR(dir_stat.st_mode):
# abort the execution
sys.exit(1)
# Verify the owner
if dir_stat.st_uid != os.getuid():
# abort the execution
sys.exit(1)
# Verify the permissions
if (dir_stat.st_mode & 0o077) != 0:
# abort the execution
sys.exit(1)
Frequently Asked Questions
- What is CVE-2026-53759? CVE-2026-53759 is a low-severity security vulnerability in linuxfabrik-lib (pip), affecting versions < 4.2.0. It is fixed in 4.2.0.
- Which versions of linuxfabrik-lib are affected by CVE-2026-53759? linuxfabrik-lib (pip) versions < 4.2.0 is affected.
- Is there a fix for CVE-2026-53759? Yes. CVE-2026-53759 is fixed in 4.2.0. Upgrade to this version or later.
- Is CVE-2026-53759 exploitable, and should I be worried? Whether CVE-2026-53759 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-53759 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-53759? Upgrade
linuxfabrik-libto 4.2.0 or later.